The present invention relates to strain gage load cells for weighing and force measurement, and especially to an improved design of a shear beam load cell and a new method for making such load cells.
A shear beam load cell comprises a rectangular beam of load cell quality metal alloy, which has one end arranged to be supported on a base in cantilever fashion, and a free end arranged to support a vertical load. Between the supported end and the loaded end there are opposed lateral blind holes forming an I-beam section with a narrow vertical web aligned with the longitudinal axis of the cantilevered beam. Strain gages aligned to measure principal stress due to shear strain are bonded to both sides of the web, and are connected in a bridge circuit for measuring the vertical load applied to the load cell.
Known designs for shear beam load cells can provide high accuracy with low sensitivity to off-center loads, torque and horizontal forces affecting the load application area, so they are widely used in heavy duty weighing applications. The machining of known shear beam load cells requires multiple machining set-ups, however, so the machining cost is a large portion of the cost for such load cells.